The invention relates generally to fiber quality measurements for cotton classing and, more particularly, to image-based instrument measurements of Color and Trash.
Cotton standards are supported by the United States Department of Agriculture (USDA) through its Agricultural Marketing Service (AMS). Cotton standards, and the corresponding classing of cotton, are of great importance in determining the market value of a particular bale of cotton, as well as determining suitability of a particular bale of cotton from a gin for subsequent processing at a particular mill in view of the products and processes of that mill. AMS is responsible for preparing and maintaining such cotton standards and does so in its Standards Section located in Memphis, Tennessee.
In 1923, the United States and nine European countries entered into the Universal Cotton Standards Agreement. From that time, up until approximately 1965, USDA/AMS cotton classing xe2x80x9cmeasurementsxe2x80x9d based on the Universal Standards were made entirely by humans. The human measurements included xe2x80x9cgrade,xe2x80x9d xe2x80x9cextraneous matterxe2x80x9d (such as bark and grass), xe2x80x9cpreparationxe2x80x9d (which relates to smoothness of the sample) and xe2x80x9cstaple lengthxe2x80x9d (long fiber content). Instrument-based cotton classing was introduced in 1965, beginning with micronaire, followed in 1980 by High Volume Instruments (HVI), which added measurements of length and strength. HVIs currently measure the fiber qualities of Micronaire, Length, Strength, Color and Trash. Instruments for measuring Color (Rd, +b and +a, which refer to xe2x80x9creflectiveness,xe2x80x9d xe2x80x9cyellownessxe2x80x9d and xe2x80x9crednessxe2x80x9d) and Trash (% Area) have also been developed, but Human Classer measurements of Color and Trash are still generally employed because of certain deficiencies in these methods.
Prior to 1993, Classer""s Grade was a combination of color and leaf trash. In USDA/AMS classing, the human Classer now separately calls a color grade and a leaf grade. These Classer""s calls for color and leaf grade are still the official measurements, along with a Classer""s call about xe2x80x9cExtraneous Matterxe2x80x9d and xe2x80x9cPreparation.xe2x80x9d Although currently unofficial, instrumental measurements of Color and Trash, as well as exploratory measurements of Short Fiber Content are made, however deficient, both to satisfy mill requests for the information and to lay the foundation and to create demand for improvements.
The Classer measurements of color, trash, preparation and extraneous matter are primarily visual, and measurements of staple length are both tactile and visual. It is appropriate to call all human classifications xe2x80x9cmeasurementsxe2x80x9d in a broad sense. This is because Classers are rigorously trained to compare their observations to cotton standards immediately available to them. That is, they measure first, by comparison, then put the sample into a xe2x80x9cclass.xe2x80x9d If a Classer has any doubt about a classing call, the Classer can, sample in hand, go to a set of standards boxes to refresh the Classer""s memory to improve the xe2x80x9ccallxe2x80x9d by comparison to the standards for Grade and Staple.
Considering in particular the current methods of human visual fiber quality measurements, the Classer holds a sample from a bale and visually examines its appearance in good, meaning standardized, illumination. Making the measurements of Color Grade and Leaf Grade physiologically and psychologically amounts to comparing the images falling on the retinas and perceived by the brain with images from memory or, for confirmation, images from physical standards. The procedures of making such measurements are learned in extensive training. xe2x80x9cClasser""s Callxe2x80x9d means that the Classer has measured the object and judged it to fall within or near to a standard or, if not, he or she comments why.
In embodiments of the invention, an optical imaging device having a defined object field of view acquires an image for classifying an unknown sample of cotton. The unknown sample of cotton is placed in the object field of view, as well as at least one reference material. As a result, the optical imaging device acquires images of both the unknown sample of cotton and the reference material in the same field of view, at the same time and under the same measurement conditions.
In an instrument classification embodiment, an instrumental xe2x80x9ccallxe2x80x9d or classification of the sample under test is made without reconstructing an image of the object field for human viewing.
In a human classification embodiment, the image of the entire object field, including the sample under test and at least one reference material, is reconstructed for human classification, either locally or remotely. When the image file is transferred over the internet to a remote location, we refer to the embodiments as xe2x80x9cInternet Classing.xe2x80x9d
Inclusion of at least one reference material, having known and traceable optical properties in the object field is an important feature in both embodiments, and overcome the deficiencies of prior art methods. It is particularly advantageous to use reference materials which are similar to the samples under test. Thus cottons, whose color or trash properties are established by AMS or others, are included as reference materials. In the instrument classification, algorithms match the unknown to the knowns.
Embodiments of the invention can employ, as the optical imaging device, a high quality color scanner intended for office or graphics arts use in scanning documents. In the context of the invention, the inclusion of at least one reference material in the object field is not intended to refer to the usual and conventional calibration xe2x80x9cstripxe2x80x9d included in such color scanners. Such a calibration xe2x80x9cstripxe2x80x9d is internal to the scanner, and is generally employed to calibrate the intensity of the illumination within the scanner. The internal scanner calibration xe2x80x9cstripxe2x80x9d is not part of the acquired image data.